This is just a simple problem finding out the outer surface charge, the inner surface charge and the net charge. Net charge by definition means the difference between two charges. In this case, the formula that is applicable here is outer surface charge = total net charge - inner cavity surface charge. Since we are given already with the net charge equal to 12.0 x10-6 C and the inner charge magnituude f 3.7 x10-6 C, the the total charge must be outer charge is +10x10(-6)) - (-3.0x10(-6)) = +1.3x10(-5) C.
Charges are measured in coloumbs and most likely exist on surfaces of entities like particles, walls etc.
Answer:
The length of the wire is 83.2 m.
Explanation:
Given that,
Power of heater, P = 300 W
Voltage, V = 110 V
The resistivity of nichrome wire is, 
The electric power of a wire is given by :

Area of cross section of the wire is :

Resistance of a material is given by :

So, the length of the wire is 83.2 m. Hence, this is the required solution.
The temperature of the gas is 41.3 °C.
Answer:
The temperature of the gas is 41.3 °C.
Explanation:
So on combining the Boyle's and Charles law, we get the ideal law of gas that is PV=nRT. Here P is the pressure, V is the volume, n is the number of moles, R is gas constant and T is the temperature. The SI unit of pressure is atm. So we need to convert 1 Pa to 1 atm, that is 1 Pa = 9.86923×
atm. Thus, 171000 Pa = 1.6876 atm.
We know that the gas constant R = 0.0821 atmLMol–¹K-¹. Then the volume of the gas is given as 50 L and moles are given as 3.27 moles.
Then substituting all the values in ideal gas equation ,we get
1.6876×50=3.27×0.0821×T
Temperature = 
So the temperature is obtained to be 314.3 K. As 0°C = 273 K,
Then 314.3 K = 314.3-273 °C=41.3 °C.
Thus, the temperature is 41.3 °C.
Initial volume of mercury is
V = 0.1 cm³
The temperature rise is 35 - 5 = 30 ⁰C = 30 ⁰K.
Because the coefficient of volume expansion is 1.8x10⁻⁴ 1/K, the change in volume of the mercury is
ΔV = (1.8x10⁻⁴ 1/K)*(30 ⁰K)(0.1 cm³) = 5.4x10⁻⁴ cm³
The cross sectional area of the tube is
A = 0.012 mm² = (0.012x10⁻² cm²).
Therefore the rise of mercury in the tube is
h = ΔV/A
= (5.4x10⁻⁴ cm³)/(0.012x10⁻² cm²)
= 4.5 cm
Answer: 4.5 cm